package com.rocketmq.base.example;

import org.apache.rocketmq.client.impl.consumer.MQConsumerInner;

import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

/**
 * @Auther: tianchao
 * @Date: 2021/9/3 14:03
 * @Description:
 */
public class Test {
    public static void main(String[] args) {
        ConcurrentMap<String,String> consumerTable = new ConcurrentHashMap<String, String>();
        String s = consumerTable.putIfAbsent("a", "b");
        System.out.println(s);
        String s1 = consumerTable.putIfAbsent("a", "c");
        System.out.println(s1);
    }
}
